Pedogenesis, Chemical Weathering and Processes of Formation of Some Supergene Ore Deposits

Geochemical characterization of the largest upland lake of the Brazilian Amazonia: Impact of provenance and processes

“…In this case, Fe is relatively enriched because some quantities of Al are dissolved during desilication (Schellmann, 1981). Also, the mobility of Fe and Al are highly influenced by pH and Eh (Lelong et al, 1976). These factors lead to separation of Fe and Al and formation of secondary minerals which control the chemical behavior of trace elements in laterites under different environmental conditions (Lelong et al, 1976;El-Leil et al, 2017).…”

Weathering crusts on peridotite

“…The brown weathering crusts on peridotite have been reported and described from localities worldwide (Lauder 1965;Evzerov et al 2007;Bucher-Nurminen 1991;Lindahl and Nilsson 2008;Nilsson et al 2005;Bucher 2012;Yoshida et al 2011). In wet and warm climates, peridotite weathering may form very deep laterite-type soils (several meters) and Ni deposits (Lelong et al 1976;Sagapoa et al 2011). Intense weathering of peridotite may form a series of rather unusual secondary minerals from olivine including iddingsite, opal, chalcedony, magnesite, nontronite, and kaolinite (Edwards 1938;Boev et al 2009).…”

The Lateritic Nickel-Ore Deposits

“…In addition to vertical drainage, a lateral circulation of the soil solutions can start and it can even become major in very plane surfaces. The upper part of the landscape then plays an equivalent role at the top of a profile (leached environment); the downstream part being equivalent to the-base of a profile (confined environment ;Millot 1964;Tardy 1969;Lelong et al 1976). Ni which accumulates at the base of the downstream profiles, is not only imported from the top of the profile located above, but also from the upstream profile.…”